Local distribution of the effects of sympathetic stimulation on cerebral blood flow in the rat.
Although the density of sympathetic fibres on the cerebral vessels varies regionally, the cerebral circulatory effects of electrical stimulation of these fibres on the cerebral circulation have not been mapped in detail. In the present study the effects of sympathetic stimulation on local cerebral blood flow were examined in urethane anaesthetized rats using autoradiographic techniques. Initial experiments determined that unilateral stimulation of the superior cervical ganglion altered cerebral circulatory dynamics to an extent sufficient to reduce cerebral venous pressure by 1.1 +/- 0.2 mm Hg. Local cerebral blood flow was measured with iodo[14C]antipyrine autoradiography in 4 groups: (1) sham; (2) sham + unilateral sympathetic nerve section; (3) unilateral stimulation of the superior cervical ganglion; and (4) unilateral sympathetic stimulation + contralateral sympathetic nerve section. In the sham animals, local cerebral blood flow was equivalent in the innervated and denervated hemispheres. During stimulation plus contralateral nerve section, a regionally heterogeneous response to sympathetic stimulation was observed. Local cerebral blood flow was reduced 11-19% on the stimulated side in over one half (15/28) of the regions examined (e.g. thalamic nuclei and caudate nucleus). In general, ipsilateral reductions in flow occurred in the territory supplied by the middle cerebral, posterior cerebral and posterior communicating arteries and their branches. Cerebral blood flow was symmetrical in regions supplied by the basilar and anterior cerebral arteries and in some midline structures.
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Division of Neonatology, Hospital for Sick Children, Toronto, Ont., Canada.
D000818:Animals; D000983:Antipyrine / Q000031:analogs & derivatives; D001345:Autoradiography; D001794:Blood Pressure; D001921:Brain / Q000098:blood supply*; D002250:Carbon Radioisotopes; D002560:Cerebrovascular Circulation; D003714:Denervation; D004558:Electric Stimulation; D005728:Ganglia, Sympathetic / Q000502:physiology*; D008297:Male; D009412:Nerve Fibers / Q000502:physiology; D009928:Organ Specificity; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D012039:Regional Blood Flow
D002250:Carbon Radioisotopes; D000983:Antipyrine; C008135:iodoantipyrine